IIUYC, you're saying the fairly small Bigloo community doesn't have much
to do, and would be ready and eager to take on a fairly arbitrary
project, such as SvnWiki. Whereas the Chicken community is larger, but
people all have their own areas of specialty, and are pretty busy with
their own concerns. To this I say: I seriously doubt the Bigloo
volunteers have time on their hands like you suggest. You'd better go
ask 'em before billing them as a readily available labor pool. It is
far more likely that they have as much energy per volunteer as any open
source community: very little . And we do know that Bigloo's community
is smaller, with less effort made towards the infrastructural concerns
(wikis, extensions, cross-platform builds) that make systems more widely
useful and attract more developers.

[...]
Bigloo's build is based on GNU Autoconf, which is much easier to
program with when dealing with a large project such as a web page.

Why is that? I presume you're speaking from experience, programming
both GNU Autoconf and CMake "in the large?" Or are you speaking from
prejudice, that you know GNU Autoconf, lotsa other people know GNU
Autoconf, and you have no idea if CMake offers any advantages or
disadvantages, other than it's not GNU Autoconf? FWIW CMake is good
enough for KDE, and for them it was better than SCons, so I'm not
inclined to believe any a priori assertion that there's a problem with
programming CMake in the large. I'd like to hear specific details about
what's an enabler or disabler in either build system.

Why is Bigloo or Chicken's build even an issue here? Since when do we
build Scheme itself to implement a Scheme application? Or is there
something exotic in SvnWiki's principle of operation that I'm not aware
of? I wasn't aware that the build system was of any concern to the
Scheme programmer at all, other than it builds, it builds on my system,
and it builds without me tearing my hair out.

Finally, a major advantage of Bigloo over Chicken Scheme is that
Bigloo does not have Scheme in its name. This is critical for your
goals.

I really doubt that, considering that "Bigloo is a Scheme
implementation..." is the 1st statement on its homepage. If marketing
is really the dealbreaker, we can canonically refer to "Chicken" when
dealing with people who are scared of Scheme. But I think this is
silliness. It's not that it's Scheme. It's that it's not a mainstream
web language, i.e. Ruby, Python, PHP, Java, or Perl, that lotsa people
already know. You simply aren't going to get a lot of people arseing
themselves to learn a new, non-mainstream, somewhat weird language. The
labor pool is inherently limited.